The Apple of Eden is the Apple-shaped Piece of Eden sought by the Templars in Assassin's Creed II.
Pieces of Eden are advanced artifacts created by the Isu, the technologically powerful precursor civilization in Assassin's Creed lore. The Apples can influence perception and behavior, making them valuable to groups seeking control over populations.
In Assassin's Creed II, Ezio encounters the Apple during the struggle involving Rodrigo Borgia and the Templars. The artifact is connected to the game's larger mythology and to the conflict between those who favor freedom and those who seek order through domination.
The series includes several other Pieces of Eden, including the Staff, Swords, and Shrouds. These are separate artifact types, so the broader phrase “Piece of Eden” is not as specific as the Apple of Eden. The Apple is also central to the first Assassin's Creed game.